All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Most scholars are of the view that whoever undertakes a lawful journey of a distance of 83 kilometers (or more), is allowed to shorten the four Rak'ah prayers to two (i.e. the Thuhr, ‘Asr, and ‘Isha). Based on this, you can shorten four Rak’ah prayers because you are eligible to that, and your daily journey does not affect it.
Likewise, you are not obliged to make intention for Qasr (shortening of the prayer) until when you are doing the first Takbeer of the prayer you are shortening. Making intention should be with the heart.
As for uttering that, it has no basis in Islamic Law.
Note: the Fajr prayer and the Maghrib prayer are not shortened.
Allah knows best.